scholarly journals Cytoplasmic labile iron accumulates in aging stem cells perturbing a key rheostat for identity control

2021 ◽  
Author(s):  
Yun-Ruei Kao ◽  
Jiahao Chen ◽  
Rajni Kumari ◽  
Madhuri Tatiparthy ◽  
Yuhong Ma ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Cell Division ◽  
Adult Stem Cells ◽  
Iron Homeostasis ◽  
Molecular Mechanisms ◽  
Labile Iron Pool ◽  
Wide Range ◽  
Labile Iron ◽  
Iron Pool

Bone marrow resident and rarely dividing haematopoietic stem cells (HSC) harbour an extensive self-renewal capacity to sustain life-long blood formation; albeit their function declines during ageing. Various molecular mechanisms confer stem cell identity, ensure long-term maintenance and are known to be deregulated in aged stem cells. How these programs are coordinated, particularly during cell division, and what triggers their ageing-associated dysfunction has been unknown. Here, we demonstrate that HSC, containing the lowest amount of cytoplasmic chelatable iron (labile iron pool) among hematopoietic cells, activate a limited iron response during mitosis. Engagement of this iron homeostasis pathway elicits mobilization and β-oxidation of arachidonic acid and enhances stem cell-defining transcriptional programs governed by histone acetyl transferase Tip60/KAT5. We further find an age-associated expansion of the labile iron pool, along with loss of Tip60/KAT5-dependent gene regulation to contribute to the functional decline of ageing HSC, which can be mitigated by iron chelation. Together, our work reveals cytoplasmic redox active iron as a novel rheostat in adult stem cells; it demonstrates a role for the intracellular labile iron pool in coordinating a cascade of molecular events which reinforces HSC identity during cell division and to drive stem cell ageing when perturbed. As loss of iron homeostasis is commonly observed in the elderly, we anticipate these findings to trigger further studies into understanding and therapeutic mitigation of labile iron pool-dependent stem cell dysfunction in a wide range of degenerative and malignant pathologies.

scholarly journals Cytoplasmic Labile Iron Accumulates in Aging Stem Cells Perturbing a Key Rheostat for Identity Control

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 3282-3282
Author(s):  
Yun-Ruei Kao ◽  
Jiahao Chen ◽  
Rajni Kumari ◽  
Madhuri Tatiparthy ◽  
Yuhong Ma ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Iron Homeostasis ◽  
Cell Function ◽  
Intracellular Iron ◽  
Hematopoietic Stem ◽  
Labile Iron Pool ◽  
Redox Active ◽  
Labile Iron ◽  
Iron Pool

Abstract Bone marrow resident and rarely dividing hematopoietic stem cells (HSC) harbor an extensive self-renewal capacity to sustain life-long blood formation, albeit their function declines during ageing. Various molecular mechanisms confer stem cell identity, ensure long-term maintenance and are known to be deregulated in aged stem cells. How these programs are coordinated, particularly during cell division, and what triggers their ageing-associated dysfunction has been unknown. We have previously uncovered that iron chelator exposure increases the number of functional HSC ex vivo and in vivo (Kao et al., Science Transl Med 2018). While ensuring a sufficient amount of redox active, readily available iron which is required in numerous electron transfer reactions governing fundamental cellular processes, cells tightly regulate the size of the intracellular labile iron pool (LIP) to limit adverse ROS generation. Perturbations in the ability to limit intracellular iron is detrimental for cells and known to compromise HSC maintenance and function via altered redox signaling and increased macromolecule oxidation and damage. The HSC stimulatory effects of iron chelator (IC) treatment and the well characterized central roles of redox active intracellular iron in sustaining basic cell function prompted us to examine a potential regulatory role of the LIP in controlling somatic stem cell function. In this study, we quantified LIP in young and aged HSC and monitored iron homoeostasis pathway activation, hallmarked by the stabilization of transferrin receptor (Tfrc) mRNA, in stem cells for which we developed a single molecule RNA fluorescence in situ hybridization (smRNA FISH) assay enabling the quantification of Tfrc dynamics with unparalleled resolution and sensitivity. We have further used experimental LIP modulation in primary hematopoietic stem cell models to characterize the consequences of iron homeostasis pathway activation in young and aged stem cells; and employed integrated comparative quantitative transcriptomics (single cell RNA-seq) and proteomics along with genetic and pharmacological rescue models to identify the consequences and mechanisms of LIP size alterations. Our findings demonstrate that HSC, containing the lowest amount of cytoplasmic chelatable iron hematopoietic cells, activate a limited iron response during mitosis. Engagement of this iron homeostasis pathway elicits mobilization and β-oxidation of arachidonic acid and enhances stem cell-defining transcriptional programs governed by histone acetyl transferase Tip60/KAT5. We further find an age-associated expansion of the labile iron pool, along with loss of Tip60/KAT5-dependent gene regulation to contribute to the functional decline of ageing HSC, which can be mitigated by iron chelation. Together, our work reveals cytoplasmic redox active iron as a novel rheostat in adult stem cells; it demonstrates a role for the intracellular labile iron pool in coordinating a cascade of molecular events which reinforces HSC identity during cell division and to drive stem cell ageing when perturbed. As loss of iron homeostasis is commonly observed in the elderly, we anticipate these findings to trigger further studies into understanding and therapeutic mitigation of labile iron pool-dependent hematopoietic stem cell dysfunction in a wide range of degenerative and malignant hematologic pathologies. Disclosures D'Alessandro: Omix Thecnologies: Other: Co-founder; Rubius Therapeutics: Consultancy; Forma Therapeutics: Membership on an entity's Board of Directors or advisory committees.

Calcein and the Labile Iron Pool.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1546-1546
Author(s):  
Shan Soe-Lin ◽  
Joan L. Buss ◽  
Evelyn Tang ◽  
Prem Ponka
Keyword(s):  
Iron Homeostasis ◽  
Iron Chelator ◽  
Acetoxymethyl Ester ◽  
Iron Regulatory Proteins ◽  
Labile Iron Pool ◽  
Cellular Iron ◽  
Labile Iron ◽  
The Difference ◽  
Iron Pool ◽  
Cellular Iron Homeostasis

Abstract The labile iron pool is a putative cytosolic compartment of loosely bound, redox-active, chelator-accessible iron. Iron contained within this pool is thought to influence the activity of iron regulatory proteins (IRPs), which bind to iron response elements (IRE) during low iron conditions; this association blocks the translation of ferritin mRNA, and stabilizes transferrin receptor mRNA. High levels of labile iron have been shown to promote oxidative stress. As this pool has such profound effects upon cellular iron homeostasis, there has been great interest in the development of methods to measure labile iron. Calcein, a fluorescent iron chelator, has been widely used to monitor the labile iron pool. When the non-fluorescent acetoxymethyl ester moiety (calcein-AM), enters cells, it is immediately cleaved by cytosolic esterases to its cell-impermeable, fluorescent calcein form. Iron binding to calcein quenches its fluorescence, which can subsequently be recovered following the loss of its iron to a stronger chelator. The difference in fluorescence between the bound and unbound calcein forms is thought to be proportional to the labile iron pool itself. While this method has been commonly exploited, it is unknown whether calcein may over-estimate the size of the labile pool by stripping iron from sources where it may be loosely bound, or by intercepting iron during its passage from one compartment to another. Although it is believed that calcein exerts very little direct influence on cellular iron homeostasis and acts only as a passive sensor of labile iron, some recent evidence from our lab indicates that this may not be the case. We have observed that incubation with calcein results in the activation of IRP-2 and stabilization of HIF-1α, a potent physiological regulator governing the expression of genes involved in oxygen sensing and iron metabolism. Furthermore, we have found that the size of the labile iron pool as measured by calcein was proportional to the amount of calcein loaded in HeLa and K562 cell lines. These findings suggest that calcein may be able to perturb cellular iron homeostasis, and may not accurately reflect the size of the labile iron pool. While calcein may still be used for comparative purposes under identically controlled conditions, its usefulness as a quantifying agent should be regarded with caution.

scholarly journals Stem Cell and Markers

2019 ◽  
Vol 1 (1) ◽  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Embryonic Stem Cells ◽  
Adult Stem Cells ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Embryonic Stem ◽  
Stem Cell Markers ◽  
Cell Markers ◽  
Wide Range

Stem cells have the ability to go through various cell divisions and also maintain undifferentiated state. Stem cells are Embryonic (Pluripotent) and adult stem cells. Pluripotent stem cells give rise to all tissues such as ectoderm, mesoderm and endoderm. Embryonic stem cells isolated from inner cell mass of embryo blastocyst. Adult stem cells are also undifferentiated cells present in adult organisms and repair the tissue when damaged occurs but number in less. Adult stem cells are present in bone marrow, adipose tissue, blood and juvenile state umbilical cord and tissue of specific origin like liver, heart, intestine and neural tissue. Embryonic stem cells from blastocyst have the ethical problems and tumorogenecity. These can be identified by flow cytometry. There are wide range of stem cell markers which are useful in identifying them. Most of the pluripotent cell markers are common with tumor cell markers which throws a challenge for certainty.

scholarly journals Opposing Wnt and JAK-STAT signaling gradients define a stem cell domain by regulating spatially patterned cell division and differentiation at two borders

2020 ◽  
Author(s):  
David Melamed ◽  
Daniel Kalderon
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Cell Division ◽  
Adult Stem Cells ◽  
Wnt Pathway ◽  
Opposite Polarity ◽  
Follicle Cells ◽  
Pathway Activity ◽  
Stat Signaling ◽  
Stat Pathway

AbstractMany adult stem cells are maintained as a community by population asymmetry, wherein stochastic actions of individual cells collectively result in a balance between stem cell division and differentiation. We have used Drosophila Follicle Stem Cells (FSCs) as a paradigm to explore the extracellular niche signals that define a stem cell domain and organize stem cell behavior. FSCs produce transit-amplifying Follicle Cells (FCs) from their posterior face and quiescent Escort Cells (ECs) to their anterior. Here we show that JAK-STAT pathway activity, which declines from posterior to anterior, dictates the pattern of divisions over the FSC and EC domains, promotes more posterior FSC locations and conversion to FCs, while opposing EC production. A Wnt pathway gradient of opposite polarity promotes more anterior FSC locations and EC production and opposes FC production. Promotion of both FSC division and conversion to FCs by JAK-STAT signaling buffers the effects of genetically altered pathway activity on FSC numbers and balances the four-fold higher rate of differentiation at the posterior face of the FSC domain with a higher rate of FSC division in the most posterior layer. However, genetic elimination of Wnt pathway activity exacerbated elevated FC production resulting from increased JAK-STAT pathway activity, leading to rapid FSC depletion despite high rates of division. The two pathways combine to define a stem cell domain through concerted effects on FSC differentiation to ECs (high Wnt, low JAK-STAT) and FCs (low Wnt, high JAK-STAT) at each end of opposing signaling gradients, further enforced by quiescence at the anterior border due to declining JAK-STAT pathway activity.

scholarly journals Effect of Age and Lipoperoxidation in Rat and Human Adipose Tissue-Derived Stem Cells

2020 ◽  
Vol 2020 ◽  
pp. 1-20
Author(s):  
Mario F. Muñoz ◽  
Sandro Argüelles ◽  
Francesco Marotta ◽  
Mario Barbagallo ◽  
Mercedes Cano ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Stem Cells ◽  
Adipose Tissue ◽  
Stem Cell ◽  
Cell Biology ◽  
Adult Stem Cells ◽  
Elongation Factor ◽  
Human Adipose Tissue ◽  
Wide Range ◽  
Proliferation And Differentiation

A wide range of clinical applications in regenerative medicine were opened decades ago with the discovery of adult stem cells. Highly promising adult stem cells are mesenchymal stem/stromal cells derived from adipose tissue (ADSCs), primarily because of their abundance and accessibility. These cells have multipotent properties and have been used extensively to carry out autologous transplants. However, the biology of these cells is not entirely understood. Among other factors, the regeneration capacity of these cells will depend on both their capacity of proliferation/differentiation and the robustness of the biochemical pathways that allow them to survive under adverse conditions like those found in damaged tissues. The transcription factors, such as Nanog and Sox2, have been described as playing an important role in stem cell proliferation and differentiation. Also, the so-called longevity pathways, in which AMPK and SIRT1 proteins play a crucial role, are essential for cell homeostasis under stressful situations. These pathways act by inhibiting the translation through downregulation of elongation factor-2 (eEF2). In order to deepen knowledge of mesenchymal stem cell biology and which factors are determinant in the final therapeutic output, we evaluate in the present study the levels of all of these proteins in the ADSCs from humans and rats and how these levels are affected by aging and the oxidative environment. Due to the effect of aging and oxidative stress, our results suggest that before performing a cell therapy with ADSCs, several aspects reported in this study such as oxidative stress status and proliferation and differentiation capacity should be assessed on these cells. This would allow us to know the robustness of the transplanted cells and to predict the therapeutic result, especially in elder patients, where probably ADSCs do not carry out their biological functions in an optimal way.

scholarly journals Oxidative stress and disruption of labile iron generate specific auxotrophic requirements in Salmonella enterica

Microbiology ◽  
2009 ◽  
Vol 155 (1) ◽  
pp. 295-304 ◽  
Author(s):  
Michael P. Thorgersen ◽  
Diana M. Downs
Keyword(s):  
Oxidative Stress ◽  
Mutant Strain ◽  
Iron Homeostasis ◽  
Sulfite Reductase ◽  
Nutritional Requirements ◽  
Labile Iron Pool ◽  
Genetic Perturbations ◽  
A Cell ◽  
Labile Iron ◽  
Iron Pool

The response of a cell to integrated stresses was investigated using environmental and/or genetic perturbations that disrupted labile iron homeostasis and increased oxidative stress. The effects of the perturbations were monitored as nutritional requirements, and were traced to specific enzymic targets. A yggX gshA cyaY mutant strain required exogenous thiamine and methionine for growth. The thiamine requirement, which had previously been linked to the Fe–S cluster proteins ThiH and ThiC, was responsive to oxidative stress and was not directly affected by manipulation of the iron pool. The methionine requirement was associated with the activity of sulfite reductase, an enzyme that appeared responsive to disruption of labile iron homeostasis. The results are incorporated in a model to suggest how the activity of iron-containing enzymes not directly sensitive to oxygen can be decreased by oxidation of the labile iron pool.

scholarly journals Division-independent differentiation mandates proliferative competition among stem cells

2017 ◽  
Author(s):  
Amy Reilein ◽  
David Melamed ◽  
Simon Tavaré ◽  
Daniel Kalderon
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Cell Division ◽  
Experimental Evidence ◽  
Adult Stem Cells ◽  
Proliferation Rate ◽  
Quantitative Modeling ◽  
Stem Cell Division ◽  
Follicle Stem Cells ◽  
The Impact

SUMMARYCancer-initiating gatekeeper mutations that arise in stem cells would be especially potent if they stabilize and expand an affected stem lineage (1, 2). It is therefore important to understand how different stem cell organization strategies promote or prevent variant stem cell amplification in response to different types of mutation, including those that activate stem cell proliferation. Stem cell numbers can be maintained constant while producing differentiated products through individually asymmetric division outcomes or by population asymmetry strategies, in which individual stem cell lineages necessarily compete for niche space. We considered alternative mechanisms underlying population asymmetry and used quantitative modeling to predict starkly different consequences of altering proliferation rate: a variant, faster-proliferating mutant stem cell should compete better only when stem cell division and differentiation are independent processes. For most types of stem cell it has not been possible to ascertain experimentally whether division and differentiation are coupled. However, Drosophila Follicle Stem Cells (FSCs) provided a favorable model system to investigate population asymmetry mechanisms and also for measuring the impact of altered proliferation on competition. We found from detailed cell lineage studies that FSC division and FSC differentiation are not coupled. We also found that FSC representation, reflecting maintenance and amplification, was highly responsive to genetic changes that altered only the rate of FSC proliferation. The FSC paradigm therefore provides definitive experimental evidence for the general principle that relative proliferation rate will always be a major determinant of competition among stem cells specifically when stem cell division and differentiation are independent.SIGNIFICANCEAdult stem cells support tissue maintenance throughout life but they also can be cells of origin for cancer, allowing clonal expansion and long-term maintenance of the first oncogenic mutations. We considered how a mutation that increases the proliferation rate of a stem cell would affect the probability of its competitive survival and amplification for different potential organizations of stem cells. Quantitative modeling showed that the key characteristic predicting the impact of relative proliferation rate on competition is whether differentiation of a stem cell is coupled to its division. We then used Drosophila Follicle Stem Cells to provide definitive experimental evidence for the general prediction that relative proliferation rates dictate stem cell competition specifically for stem cells that exhibit division-independent differentiation.

scholarly journals Implication of Dietary Iron-Chelating Bioactive Compounds in Molecular Mechanisms of Oxidative Stress-Induced Cell Ageing

Antioxidants ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 491
Author(s):  
Alexandra Barbouti ◽  
Nefeli Lagopati ◽  
Dimitris Veroutis ◽  
Vlasios Goulas ◽  
Konstantinos Evangelou ◽  
...  
Keyword(s):  
Free Radical ◽  
Molecular Mechanisms ◽  
Cellular Systems ◽  
Free Radical Theory ◽  
Radical Theory ◽  
Cellular Protection ◽  
Lipofuscin Accumulation ◽  
Labile Iron Pool ◽  
Labile Iron ◽  
Iron Pool

One of the prevailing perceptions regarding the ageing of cells and organisms is the intracellular gradual accumulation of oxidatively damaged macromolecules, leading to the decline of cell and organ function (free radical theory of ageing). This chemically undefined material known as “lipofuscin,” “ceroid,” or “age pigment” is mainly formed through unregulated and nonspecific oxidative modifications of cellular macromolecules that are induced by highly reactive free radicals. A necessary precondition for reactive free radical generation and lipofuscin formation is the intracellular availability of ferrous iron (Fe2+) (“labile iron”), catalyzing the conversion of weak oxidants such as peroxides, to extremely reactive ones like hydroxyl (HO•) or alcoxyl (RO•) radicals. If the oxidized materials remain unrepaired for extended periods of time, they can be further oxidized to generate ultimate over-oxidized products that are unable to be repaired, degraded, or exocytosed by the relevant cellular systems. Additionally, over-oxidized materials might inactivate cellular protection and repair mechanisms, thus allowing for futile cycles of increasingly rapid lipofuscin accumulation. In this review paper, we present evidence that the modulation of the labile iron pool distribution by nutritional or pharmacological means represents a hitherto unappreciated target for hampering lipofuscin accumulation and cellular ageing.

scholarly journals Intrinsic Ability of Adult Stem Cell in Skeletal Muscle: An Effective and Replenishable Resource to the Establishment of Pluripotent Stem Cells

2013 ◽  
Vol 2013 ◽  
pp. 1-18 ◽  
Author(s):  
Shin Fujimaki ◽  
Masanao Machida ◽  
Ryo Hidaka ◽  
Makoto Asashima ◽  
Tohru Takemasa ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Stem Cells ◽  
Stem Cell ◽  
Satellite Cells ◽  
Intracellular Signaling ◽  
Adult Stem Cells ◽  
Molecular Mechanisms ◽  
Stress Injury ◽  
Self Renewal ◽  
Cell Based Therapy

Adult stem cells play an essential role in mammalian organ maintenance and repair throughout adulthood since they ensure that organs retain their ability to regenerate. The choice of cell fate by adult stem cells for cellular proliferation, self-renewal, and differentiation into multiple lineages is critically important for the homeostasis and biological function of individual organs. Responses of stem cells to stress, injury, or environmental change are precisely regulated by intercellular and intracellular signaling networks, and these molecular events cooperatively define the ability of stem cell throughout life. Skeletal muscle tissue represents an abundant, accessible, and replenishable source of adult stem cells. Skeletal muscle contains myogenic satellite cells and muscle-derived stem cells that retain multipotent differentiation abilities. These stem cell populations have the capacity for long-term proliferation and high self-renewal. The molecular mechanisms associated with deficits in skeletal muscle and stem cell function have been extensively studied. Muscle-derived stem cells are an obvious, readily available cell resource that offers promise for cell-based therapy and various applications in the field of tissue engineering. This review describes the strategies commonly used to identify and functionally characterize adult stem cells, focusing especially on satellite cells, and discusses their potential applications.

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